CobraEd:
FWIW, the 427s DO have this problem, probably worse than the 428s. I've been fighting this on my car since the day I bought it. I ran into a fellow in NJ who had an original Shelby car, completely restored, at a show at a local Ford dealer. He pulled in, turned off the engine and it puked about 1/2 pint of
antifreeze out the overflow on the expansion tank all over the ground. He walked up to my car and started to ask what I did about the overflow when mine did the same thing. The original 427-engined cars were reknown for overheating. I have since installed a catch can with a return line and am in the process of talking to Griffin about replacing the original copper/brass radiator with an aluminum one to try to resolve the overheating-in-slow-traffic problem.
Richard Hudgins:
Not meaning to cause dissention here. but I talked with some of our engine folks at work (I work for a helicopter manufacturer and we use radiators as cooling units for the engine and transmission
oil). Their statement agreed partially with yours, in that,
all things being equal , copper/brass is superior to aluminum from a heat transfer standpoint. However, as usual in engineering, all things are not equal, and the use of aluminum allows the manufacturer to build cooling tubes which are wider than possible with copper/brass, due to the increased structural rigidity of the aluminum. This allows the aluminum radiator to have more direct cooling surface area than the copper/brass. Also, the secondary cooling fins on the copper/brass radiators are soldered on; I understand that the solder inhibits the heat transfer from the primary cooling tubes to the fins, resulting in loss of efficiency. At work, we also use aluminum because it is lighter, and that is a much bigger factor in aircraft than cars.
I have talked with Bill Parham from Southern Automotive about the overheating 427 problem on several occasions. Bill built my engine and has one which is essentially identical in his Superformance demonstrator. He claims he runs it around Atlanta all year round in all kinds of traffic and never exceeds 195 degrees coolant temperature. The only difference I can see is the Superformance cars have a really nice aluminum radiator setup and my older model ERA still has the original copper/brass unit. I do note that ERA has switched to aluminum radiators in their later model Cobras and GT-40s.